If your vCenter server has a self-signed certificate, you will get a warning about this when connecting to it from vSphere PowerCLI. You can disable this warning through PowerCLI with the Set-PowerCLIConfiguration cmdlet.

Start an elevatedvSphere PowerCLI (right-click, Run as Administrator).

Enter the following cmdlet:

Set-PowerCLIConfiguration -InvalidCertificateAction Ignore

Press Enter again to confirm the change.

After making the change, new connections to the vCenter server will no longer produce a warning about the certificate.